There are a number of different types of grease guns used for the displacing of highly viscous products to a desired location at high pressures. Very often the delivery line of these units consists of a flexible hose to allow for ease of access to all greasing points. In the case were high pressure is required to overcome a high resistance due to tight tolerances inherent in bush type assemblies or blockages within the grease nipple, a swelling of the flexible hose occurs with the increase in pressure. At the end of the greasing cycle the pressure in the delivery line drops from the high pressure required for greasing to atmospheric pressure on disconnecting the grease coupler from the grease nipple. The result is that the delivery hose that absorbed extra grease as it ballooned under the higher pressure now dispels this volume to waste as it returns to its normal size under atmospheric pressure. This waste grease is also greatly compounded by the fact that there are almost always small air pockets trapped within the grease which become compressed as the pressure in the hose rises during the greasing cycle. As the delivery line is released from the grease nipple the air pockets increase volumetrically as they expand to atmospheric pressure displacing still more grease out the end of the delivery line resulting in additional waste grease. This waste increases grease consumption, becomes a fire hazard when left on machinery and becomes an environmental hazard when dropped onto the ground and allowed to enter water systems. By being able to relieve the grease under pressure in the delivery line on completion of the greasing cycle back into a predetermined reservoir a significant reduction in waste grease can be achieved, thereby creating a cost effective and environmentally friendly greasing system.
Another common feature in greasing systems is the use of a coupler known in the art as the Zerk grease coupler. This coupler allows for a high pressure connection between the grease delivery line and the greasing point (the grease nipple). A common feature of the Zerk grease coupler is that it is designed such that the pressure generated within the delivery line assists with the gripping of the grease coupler to the grease nipple. Therefore the higher the pressure generated within the delivery line the higher the force with which the coupler grips the grease nipple. In the case where the greasing cycle is complete and there remains a pressure within the delivery line the operator will need to vigorously oscillate the coupler relative to the grease nipple to cause a by-pass of grease and allow for a pressure drop in the delivery line and in turn enable the coupler to release the grease nipple. In this process the coupler and the nipple are inclined to become damaged in time as well as generating waste grease every time the pressure is relieved at the grease nipple in such a manner. With the inclusion of a pressure relief valve, on completion of the greasing cycle the pressure within the delivery line may be relieved either manually or automatically back into the grease reservoir and the coupler can be removed with ease. By using this methodology the life of both the coupler and nipples will be extended as well as a reduction in waste grease will be achieve. These positive outcomes will be directly responsible for a reduction in greasing costs.
Trials have shown that due to the benefits of this invention dramatic reductions in the waste of grease can be achieved. Furthermore the longevity of both grease couplers and grease nipples are increased significantly. Cumulatively these savings are very significant as millions upon millions of greasing cycles are completed globally every day.